In the beginning of his CD I/2, Barth discussed on whether he should start with the reality of revelation (how is the revelation of God real?) or with the possibility of revelation (how is the revelation of God possible?). Usually, Barth noted, the possibility of revelation takes precedence. But, as Barth noted again, “it would be fruitless at this point to begin considering what conditions must be fulfilled in God and in ourselves to enable this revelation to encounter us–in order subsequently to look round and see whether revelation actually encounters us in accordance with these conditions.” (I/2, 3)
To start with the possibility of revelation means that we ask first what is possible for God and then we derive whether the God has worked according to our criteria. For example, if one has decided that God can’t be human (it is not possible!), of course there is no way to believe that Jesus is truly God. Or, on the other hand, if one has decided that God can be human, of course it is plausible to believe that Jesus is truly God! For Barth, actually both approaches are basically the same, as they start with categorizing what is possible and not possible for God. And this is like putting the horse before the cart. Barth insisted (for the umpteenth time), God is free, and hence if we delineate first the possibility (or, impossibility) of revelation, basically what we are doing is limiting God’s freedom.
Thus, Barth put the discussion about the reality of revelation before the possibility of revelation. For Barth, this is in accordance with the nature of the church, as the church is the hearing church, who follows in the footsteps of the prophets and the apostles. As they listened to the Word of God, the appropriate attitude of the church is to listen as well. We will be healed when we hear.
(It also informs us of the appropriate gesture when we read the Bible or listen to a sermon, i.e., as a servant and not as a master. On the other hand, it does not mean that we should listen uncritically. But, as we listen critically, we listen critically.)